Maternal effects on offspring locomotion: influence of density and corticosterone elevation in the lizard Lacerta vivipara.

Offspring phenotype can be affected by maternal history before and during gestation. Offspring sensitivity to maternal conditions is believed to have evolved to favor preadaptation of offspring to environmental factors they are likely to encounter. Because the locomotor capacity of an individual is likely to have important fitness consequences, we examined the role of long-term and short-term prenatal conditions on offspring's locomotor performance in the lizard Lacerta vivipara. To examine long-term prenatal effects, we manipulated the density of two populations, leaving two additional populations as unmanipulated. We then collected pregnant females within these four populations (Cévennes, Massif Central, France) and kept them in the laboratory until parturition. To examine short-term prenatal effects, we manipulated the corticosterone level of half the females within each population. We took two different measurements of offspring locomotion: sprint speed and endurance. As already documented, sprint speed was positively correlated with offspring body size. Although population density significantly affected female fecundity, neither the density manipulation nor the population of origin influenced offspring phenotype. Corticosterone administered during gestation decreased juvenile sprint speed but did not affect juvenile endurance. Furthermore, we observed that the motivation to run was influenced by maternal hormonal treatment. Juveniles born from corticosterone-treated mothers needed more stimuli than those born from control mothers. We conclude, therefore, that the action of corticosterone on sprint speed could be more behavioral than physiological. Offspring phenotype as measured by endurance and sprint speed appeared partly under maternal control.